add new solutions

solutions/2/q201/solution.go

@@ -0,0 +1,21 @@
+package q201
+
+func rangeBitwiseAnd(left int, right int) int {
+	ret := left & right
+	for i := ret + 1; i < right; {
+		ret &= i
+		if ret == 0 {
+			return 0
+		}
+
+		// Find first non-zero bit
+		t := 1
+		for i|t != i {
+			t <<= 1
+		}
+		i += t
+	}
+	return ret
+}
+
+var _ = rangeBitwiseAnd